The present invention relates to a resin-made ink-jet recording head employed in an ink-jet recording apparatus and a production method of the same.
As compared with glass and metal, resins are advantageously employed for making an ink-jet recording head so that machining and assembling can be easily carried out and the production costs can be reduced.
However, when water-based ink is employed in an ink-jet recording head made of resins because the resin surface is highly water-resistant, wettability of the water-based ink decreases in contact with a resin part. Thus, when the ink is introduced into the head, bubbles remain in an ink passage, or bubbles generated in the passage tend not to be ejected even though the ejection operation is carried out. Such remaining bubbles result in decreased ink ejection and at the worst case, no dots are printed.
Accordingly, in order to improve the wettability of the resin surface of the ink passage, Japanese Patent Publication Open to Public Inspection No. 60-24957 proposes to carry out a hydrophilic treatment which generates a polar group on the surface of the resin, employing an acid treatment, plasma treatment, etc. Further, Japanese Patent Publication Open to Public Inspection No. 2-54784 proposes that while an aqueous dye solution is in contact with the surface of an ink passage, humidification is carried out and wettability is improved by previously allowing dye to adsorb onto or penetrate into the surface of the passage. Furthermore, a method is proposed in which wettability is improved by surface-grafting a hydrophilic polymer on the surface of the passages which is in contact with ink.